Brush holder for an electrical commutating machine

ABSTRACT

A brush holder for an electrical commutating machine has a brush plate and at least two brush mounts fastened on the brush plate and adapted to accommodate a carbon brushes. Each of the brush mounts has a pull-through pin coaxial with one of brush plate openings and a supporting web fastened to the brush plate. A fastening element extending through another brush plate opening and through the web opening. An insulating plate is located between the brush plate and the brush mount so that the pull-through pin projects into one insulating plate opening. An insulating part is located at a side of the brush plate and fastened by the fastening element which passes through one insulating part opening coaxial with the other brush plate opening. The insulating part has annular webs which surround the insulating part openings and project axially toward the brush plate. One of said annular webs projects through the another brush plate opening while the other of the annular webs engages through the one brush plate opening and through the one insulating plate opening in a form-fitting manner. The pull-through pin engages in the other annular web in a form-fitting fashion.

BACKGROUND OF THE INVENTION

The invention relates to a brush holder for an electrical commutatingmachine, in particular for a d.c. machine for vehicles. Moreparticularly the present invention relates to such a brush holder whichhas a brush plate supported in the frame of the commutating machine, andat least two brush mounts fastened in an insulating fashion on the brushplate and each accommodating a carbon brush and provided on theirbearing side with a pull-through pin and a supporting web.

Apart from the insulating plate arranged between the brush mount withsupporting web and brush plate, in a known brush holder of theabove-mentioned type in order to ensure the insulated fastening of thebrush mount on the brush plate, a first insulating disc is arrangedbetween the brush plate and the rivet head overreaching the brush plate,and a second insulating plate is inserted between the rivet shaft andthe bore, substantially larger in comparison thereto, in the brushplate. The entire brush mount is supported by the single rivet bolt.

In the case of extreme stresses on the commutating machine owing toimpacts, shaking or severe temperature fluctuations, such as normallyoccur in vehicle operation, it has been found in connection with suchbrush holders that the brush mounts rotate on the brush plate and assumeangular positions with respect to the commutator which are detrimentalto proper commutating.

Consequently, in the case of a brush holder that is likewise known (U.S.Pat. No. 1,490,104) two supporting webs have been provided on the brushmount, and each supporting web has been riveted to the brush plate withthe interposition of suitable insulating discs. Due to the doubleriveting, the assembly of such a brush holder is more intensive in termsof time. Again, the brush mount needs to be altered in design.

SUMMARY OF THE INVENTION

The brush holder according to the invention has the advantage that theinsulating part necessary for the insulated fastening of the brush mounton the brush plate simultaneously provides for the brush mount areliable guarantee against rotation. This guarantee against rotation isachieved due to the fact that through the annular web on the insulatingpart, on the one hand, the riveted insulating part itself is fixed inthe brush plate and, on the other hand, the pull-through pin of thebrush mount is fixed with the insulating plate on the insulating part ina form-fitting fashion. There is no change in the time-saving nature ofthe assembly, since only one rivet bolt must be riveted per brush mount.The insulating part according to the invention is a simpleinjection-moulded part or pressed part, which can be producedcost-effectively. Another insulating part is arranged on the brush plateat its side opposite to the brush mount and fixed by the same rivetbolt.

The second annular web is integrally formed in accordance with anadvantageous embodiment of the invention on the insulating part aroundthe first circular cutout produces an insulation between the rivet shaftand the edges of the bore in the brush plate. Therefore the specialinsertion into the bore of an insulating disc becomes superfluous, and afurther assembly step is saved. In this process, the annular web canterminate either flush with the brush plate or, after further passingthrough the insulating plate, flush with the insulating plate.

An enhanced guarantee against axial lifting of the brush mount from thebrush plate is achieved through additionally fastening the brush mountto the brush plate by means of a hollow rivet, which passes through thepull-through pin of the brush mount, the annular web and the secondcutout of the insulating part. Such an additional guarantee is to berecommended above all in the case of installing the commutating machinein construction vehicles, where rugged operating conditions prevail.Brief description of the drawings

The invention is explained in more detail in the following descriptionwith reference to illustrative embodiments represented in the drawing.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 shows part of a longitudinal section of a brush holder for acommutating machine,

FIG. 2 shows a plan view in the direction of the arrow A of aninsulating part of the brush holder in FIG. 1,

FIG. 3 shows a bottom view of the insulating part in FIG. 2,

FIG. 4 shows part of a longitudinal section of a brush holder inaccordance with a further illustrative embodiment,

FIG. 5 shows a part of a longitudinal section of the brush plate,insulating disc and insulating part of a brush holder in accordance withthe third illustrative embodiment.

DESCRIPTION OF PREFERRED EMBODIMENTS

A brush holder, only part of which is represented in longitudinalsection in FIG. 1, is used for an electrical commutating machine andpreferably in a d.c. machine for vehicles, such as a generator orstarter. It has a brush plate 10, which is supported unable to rotate inthe frame (not shown) of the commutating machine; Depending upon thedesign of the commutating machine with brush mounts 11 which arearranged on a circle offset by approximately the same peripheral angle,are fastened on the brush plate 10. In this arrangement, n is a wholenumber. Each brush mount 11 contains, in a known way, a carbon brush 28,which is supported in the brush mount 11 in an axially displaceablefashion parallel to the brush plate 10, and seated, under the action ofa holding spring (not represented here), on the commutator of thecommutating machine. An example for the arrangement of the brush mountson the brush plate with allocation to the commutator of the commutatingmachine is represented and described in U.S. Pat. No. 1,490,104.

The brush mount is formed of sheet metal. It carries on its bearing side11a, which faces the brush plate 10, a hollow cylindrical pull-throughpin 12. It also carries in the prolongation of the bearing side 11a asupporting web 13, which stands away at a right angle from the brushmount 11 and serves to fasten the brush mount 11 to the brush plate 10.The fastening of the brush mount 11 is done on the brush plate 10 in aninsulated fashion, to be precise by means of a single rivet bolt 14. Forthis purpose, a bore 15 is provided in the supporting web 13, and a bore16, is provided in the brush plate 10. The coaxial with the bore 15 andthe shaft 14a of the rivet bolt 14 projects, through it. A circularthrough opening 17 is provided in the brush plate 10 coaxially with thepull-through pin 12.

For the purpose of fastening the brush mount 11 in an insulated fashionto the brush plate 10, an insulating disc 18 is arranged on one side ofthe brush plate 10 between the latter and the brush mount 11 with thesupporting web 13, and an insulating part 19 is arranged on the otherside. The insulating disc 18 carries two circular cutouts 20, 21, whichare each arranged coaxially with the bore 15 and the through opening 17of the brush plate 10, respectively. The insulating part 19correspondingly carries two circular cutouts 22 and 23, which arelikewise arranged coaxially with the bore 15 and through opening 17,respectively, in the brush plate 10. Each cutout 22, 23 is surrounded byan annular web 24 and 25, respectively, each web is of one piece withthe insulating part 19 and, on the side of the insulating part 19 whichfaces the brush plate 10, projects axially as shown in FIGS. 2 and 3. Inthis arrangement, the axial length of the annular web 24 is chosen suchthat it projects through the bore 15 in the brush plate 10, andterminates flush with the brush plate 10 on the bearing side thereof forthe insulating disc 18. The external diameter of the annular web 24 issmaller in this arrangement than the clearance of the bore 15 in thebrush plate 10, while the internal diameter of the annular web 24 ischosen to be somewhat larger than the diameter of the rivet shaft 14a ofthe rivet bolt 14. The axial length of the annular web 25 is dimensionedsuch that the web passes both through the through opening 17 in thebrush plate 10 and through the cutout 21 in the insulating disc 18, andterminates flush with the insulating disc 18 on the side thereof facingthe brush mount 11. The radial annular width of the annular web 25 isdimensioned such that the annular web 25 surrounds the pull-through pin12 of the brush mount 11, which projects into the cutout 21 in theinsulating plate 18, on the one hand, and is located in a form-fittingfashion in the through opening 17 of the brush plate 10 and in thecongruent cutout 21 of the insulating plate 18, on the other hand.

To assemble the brush holder, the insulating part 19 is firstly placedupon the brush plate 10 in such a way that the annular web 24 projectsthrough the bore 15, on the one hand, and the annular web 25 projectsthrough the through opening 17 in the brush plate 10, on the other hand.The insulating plate 18 is then placed on the opposite side of the brushplate 10, and the cutout 21 of said plate being pushed over the annularweb 25, and its cutout 20 being aligned coaxially with the bore 15.Starting from the side of the insulating part 19, the rivet bolt 14 isplugged through the cutout 22, the bore 15 and the cutout 20, so thatits rivet head 14b bears against the insulating part 19, and the freeend of the rivet shaft 14a projects from the insulating plate 18. Thebrush mount 11 is now placed on the insulating plate 18, to be precisein such a way that pull-through pin 12 projects into the interior of theannular web 25 in a form-fitting fashion and the bore 16 in thesupporting web 13 embraces the rivet shaft 14a. The rivet bolt 14 issubsequently caulked, so that the brush mount 11 is supportedpermanently on the brush plate 10. The brush mount 11 is fixed andguaranteed not to rotate on the brush plate 10 by means of thepull-through pin 12 on the brush mount 11, which engages in aform-fitting fashion in the annular web 25, and by means of the annularweb 25, which projects in a form-fitting fashion both through thethrough opening 17 in the brush plate 10 and through the opening 21 inthe insulating plate 18.

In the further illustrative embodiment of a brush holder, shown in partin FIG. 4, for the purpose of additionally securing the brush mount 11on the brush plate 10, a hollow rivet 26 is led through the pullthroughpin 12, the annular web 25 and the through opening 17 in the insulatingpart 19, and is caulked on a washer 27 seated on the insulating part 19after the washer has been slipped on. Otherwise, this brush holdercorresponds to the brush holder previously described and represented inFIG. 1.

In a variant of the insulating part 19' represented in FIG. 5, theannular web 24', which surrounds the cutout 22 and is of one piece withthe insulating part 19, has an axial length such that said annular webpenetrates not only the bore 15 in the brush plate 10 but also thecutout 20 in the insulating plate 18, and thereof facing the supportingweb 13. The internal diameter of the annular web 24' is, in turn, chosento be somewhat larger than the bore 15, so that the rivet bolt 14 can beled without any problem through the interior of the annular web 24'.

It will be understood that each of the elements described above, or twoor more together, may also find a useful application in other types ofconstructions differing from the types described above.

While the invention has been illustrated and described as embodied in abrush holder for an electrical commutating machine, it is not intendedto be limited to the details shown, since various modifications andstructural changes may be made without departing in any way from thespirit of the present invention.

Without further analysis, the foregoing will so fully reveal the gist ofthe present invention that others can, by applying current knowledge,readily adapt it for various applications without omitting featuresthat, from the standpoint of prior art, fairly constitute essentialcharacteristics of the generic or specific aspects of this invention.

What is claimed as new and desired to be protected by Letters Patent isset forth in the appended claims:
 1. A brush holder for an electricalcommutating machine, in particular for a DC machine for vehicles,comprising a brush plate adapted to be supported in a frame of thecommutating machine and having first and second brush plate openingsspaced from one another; a brush mount fastened in an insulating fashionon said brush plate and adapted to support a carbon brush, said brushmount having a bearing side which faces said brush plate and carrying apull-through pin coaxial with one of said brush plate openings and asupporting web having a web opening; a fastening element extendingthrough another one of said brush plate openings and through said webopening; an insulating plate located between said brush plate and saidbrush mount and having two insulating plate openings so that saidpull-through pin projects into one of said insulating plate openings; aninsulating part located at a side of said brush plate which is oppositeto said brush mount and having two insulating part openings and fastenedby said fastening element which passes through one of said insulatingpart openings, said insulating part having annular webs which surroundsaid insulating part openings and project axially toward said brushplate so as to be of one piece with said insulating part, one of saidannular webs projecting through said another brush plate opening while aother of said annular webs engages through said one brush plate openingand through said one insulating plate opening in a form-fitting manner,said pull-through pin engaging in said other annular web in aform-fitting fashion.
 2. A brush holder as defined in claim 1, whereinsaid one of said annular webs terminates flush with said brush plate. 3.A brush holder as defined in claim 1, wherein said another of saidannular webs terminates flush with said insulating plate.
 4. A brushholder as defined in claim 1, wherein said brush mount is additionallymounted to said brush plate; and further comprising means foradditionally mounting said brush mount to said brush plate and includinga hollow rivet.
 5. A brush holder as defined in claim 4, wherein saidhollow rivet passes through said pull-through pin of said brush mountand said another of said annular webs.
 6. A brush holder as defined inclaim 5, wherein said hollow rivet has a flanged edge; and furthercomprising a washer arranged between said insulating part and saidflanged edge of said hollow rivet.